<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>使用百分比来设置元素的最大宽度</title>
    <style>
        p
        {
            max-width: 20%;
            background-color: yellow;
        }
    </style>
</head>
<body>
<p>This is some text.This is some text.This is some text.
This is some text.This is some text.This is some text.
This is some text.This is some text.This is some text.</p>
</body>
</html>